The present invention relates to a method of producing a polymer using a copper compound.
A poly-xcex1-substituted olefin derived from an xcex1-substituted olefin of the general formula CH2xe2x95x90CY1E (wherein Y1 represents a phenyl or substituted phenyl group and E represents a hydrogen atom or an alkyl group) by polymerization has so far been produced by various methods. Industrially, it is produced by adding a radical generator to a monomer and carrying out radical polymerization. However, the polymer produced by this method has a fairly broad molecular weight distribution and, because of inclusion of a low-molecular-weight polymer, it is poor in heat resistance.
On experimental scale, it can be obtained also by anionic polymerization, cationic polymerization or group transfer polymerization, for instance. Recently, a method of producing a highly stereoregular poly-xcex1-substituted olefin has been proposed and has attracted attention which comprises polymerizing an xcex1-substituted olefin of the general formula CH2xe2x95x90CY2H (wherein Y2 represents a phenyl or substituted phenyl group) using, as a polymerization catalyst component, a transition metal complex alone or a combination of a transition metal complex and an organoaluminum compound [Nobuhide Ishihara et al.: The Society of Polymer Science, Japan, Preprints, 35, 240 (1986); Japanese Kokai Publication Hei-03-72504].
A poly-xcex1-substituted olefin derived from an xcex1-substituted olefin of the general formula CH2xe2x95x90CY3Z (wherein Y3 represents a cyano group and Z represents a hydrogen atom or an alkyl group) by polymerization has so far been produced by various methods. Industrially, it is produced by radical polymerization with a radical generator added to a monomer.
As a method of polymerization by which the molecular weight and molecular weight distribution can be controlled, there have been proposed, on the laboratory level, anionic polymerization, coordination polymerization and group transfer polymerization, for instance. To be concrete, a highly stereoregular poly-xcex1-substituted olefin was produced from a monomer of the general formula CH2xe2x95x90CHY3 (wherein Y3 represents a cyano group) by a production method using an aluminum metal compound and a transition metal compound as polymerization catalysts (Japanese Kokai Publication Hei-01-79206) and a precision polymer having a narrow molecular weight distribution was produced by a polymerization reaction using an organic rare earth metal complex as a catalyst component [Akira Nakamura et al.: 43rd Meeting of The Society of Polymer Science, Japan (May 26, 1994), II-3-08].
Recently, a lactone polymer has attracted attention as biodegradable plastics.
As regards the polymerization of a lactone, anionic polymerization, coordination polymerization and group transfer polymerization, among others, have been proposed, on the laboratory level, as a polymerization method capable of controlling the molecular weight and molecular weight distribution. More specifically, there may be mentioned the method comprising carrying out polymerization using an aluminum-porphyrin complex as a polymerization initiator [Macromolecules, 14, 166 (1981)] and the method comprising using an aluminum-porphyrin complex and a Lewis acid having a bulky substituent as a polymerization initiator (Japanese Kokai Publication Hei-04-323204), among others.
A vinyl monomer has so far been polymerized by various methods. Most of the methods employed in industry comprise adding a radical generator to a vinyl monomer and carrying out radical polymerization under high temperature and high pressure conditions. Recently, anionic polymerization, coordination polymerization and group transfer polymerization, for instance, have been proposed, on the laboratory level, as polymerization methods by which the molecular weight and molecular weight distribution can be controlled.
However, the compounds used in such catalyst systems are generally unstable against oxygen and/or moisture and readily decomposable and, further, require a number of reaction steps for their synthesis. In addition, their instability makes their synthesis difficult, leading to low yields and, as a result, they constitute expensive catalyst systems.
On the other hand, as for the metal in the transition metal complex used in the catalyst systems, titanium, zirconium, hafnium and the like, which are group IV transition elements, hence early transition metals, are generally used. Recently, nickel, palladium and the like, which are group X transition elements, hence late transition metals, have also been used in spite of their rather decreased reactivity [e g. JACS, 117 (23), 6414 (1995)].
The complex containing copper as the nucleus has an advantage in that it has good stability and can be synthesized with ease. Because of its low activity due to its stability, however, it has never been studied as a polymerization catalyst. Only recently, the present inventors found and reported that a copper complex can be used as a catalyst for polymerization of carbodiimide, which is a highly polar monomer, to give a living polymer [Macromolecules, 30, 3159 (1997)].
However, a copper complex has never been applied as a polymerization catalyst for a monomer of relatively low polarity which requires reactivity.
The object of the present invention is to provide a method of producing a polymer using, as a polymerization catalyst, a copper compound which can easily be synthesized and is stable.
The present inventors have succeeded in solving the problems discussed above by using, as a polymerization catalyst component, a copper compound which can easily be synthesized and is stable.
The method of producing a polymer using a copper compound in accordance with a first aspect of the present invention (hereinafter referred to as xe2x80x9cfirst inventionxe2x80x9d) comprises using a copper compound represented by the general formula CuXn, LCuXn or L(Lxe2x80x2)CuXn (wherein L and Lxe2x80x2 each represents a ligand, X represents a halogen atom or an alkoxy, thioxy, allyloxy, amino, secondary amino, tertiary amino, cyano, nitro, alkyl or allyl group, and n represents an integer of 0 to 2) as a catalyst and/or polymerization initiator in polymerizing a vinyl monomer whose polarity value e, when expressed in terms of absolute value, is not more than 1.5.
Preferably, the method of producing a polymer comprises using a copper compound represented by the general formula LCuXna or L(Lxe2x80x2)CuXnb (wherein L and Lxe2x80x2 each represents a N-coordination compound selected from the group consisting of bisoxazoline, substituted bisoxazoline, an amidinato compound and a diimine represented by the general formula R3Nxe2x95x90CR4CR5xe2x95x90NR6 (wherein R3, R4, R5 and R6 each represents independently an alkyl, allyl, an aryl, a hydrogen atom, or a halogen atom; or at least one group of R3 and R4, R4 and R5, and R5 and R6 is combined and represents a cyclic group with the next carbon and/or nitrogen atom), or a O- and N-coordination compound; X represents a halogen atom or an alkoxy, thioxy, allyloxy, amino, secondary amino, tertiary amino, cyano, nitro, alkyl or allyl group; na represents an integer of 1 to 2; and nb represents an integer of 0 to 2) as a catalyst and/or polymerization initiator in polymerizing a vinyl monomer whose polarity value e, when expressed in terms of absolute value, is not more than 1.5.
The method of producing a polymer using a copper compound in accordance with a second aspect of the present invention (hereinafter referred to as xe2x80x9csecond inventionxe2x80x9d) comprises using a copper compound represented by the general formula CuXn, LCuXn or L(Lxe2x80x2)CuXn (wherein L and Lxe2x80x2 each represents a ligand, X represents a halogen atom or an alkoxy, thioxy, allyloxy, amino, secondary amino, tertiary amino, cyano, nitro, alkyl or allyl group, and n represents an integer of 0 to 2) as a catalyst and/or polymerization initiator in polymerizing a compound capable of polymerizing by a ring-opening reaction.
Preferably, the method of producing a polymer comprises using a copper compound represented by the general formula LCuXna or L(Lxe2x80x2)CuXnb (wherein L and Lxe2x80x2 each represents a N-coordination compound selected from the group consisting of bisoxazoline, substituted bisoxazoline, an amidinato compound and a diimine represented by the general formula R3Nxe2x95x90CR4CR5xe2x95x90NR6 (wherein R3, R4, R5 and R6 each represents independently an alkyl, allyl, an aryl, a hydrogen atom, or a halogen atom; or at least one group of R3 and R4, R4 and R5, and R5 and R6 is combined and represents a cyclic group with the next carbon and/or nitrogen atom), or a O- and N-coordination compound; X represents a halogen atom or an alkoxy, thioxy, allyloxy, amino, secondary amino, tertiary amino, cyano, nitro, alkyl or allyl group; na represents an integer of 1 to 2; and nb represents an integer of 0 to 2) as a catalyst and/or polymerization initiator in polymerizing a compound capable of polymerizing by a ring-opening reaction.
The method of producing a polymer using a copper compound in accordance with a third aspect of the present invention (hereinafter referred to as xe2x80x9cthird inventionxe2x80x9d) comprises using the copper compound together with one or more organometallic compounds selected from the group consisting of aluminoxanes, organoaluminum compounds represented by the general formula AlRmZ3-m (wherein R represents a hydrocarbon group containing 1 to 20 carbon atoms, Z represents a hydrogen or halogen atom or an alkoxy, allyloxy or siloxy group, and m is an integer of 0 to 3), boron-containing Lewis acids and boron-containing ionic compounds in the first or second invention.
In the following, the present invention is described in detail.
The vinyl monomer to be used in the present invention includes those which have a reactive double bond within the molecule and whose polarity value e, when expressed in terms of absolute value, is not more than 1.5.
The above-mentioned polarity value e is a value indicating the electron density at a double bond site. When there is an electron flow into the double bond, the polarity shows a negative value and, when an electron is being pulled by a substituent, it shows a positive value [Kobunshi Kagaku no Kiso; edited by The Society of Polymer Science, Japan, published by Tokyo Kagaku Dojin).
When the above polarity value e exceeds 1.5, the vinyl monomer is excessively high in polarity, so that the copper complex catalyst, in particular in a system in which an organometallic compound is used as a promoter, is deactivated and the polymerization reaction can no longer proceed successfully.
As the vinyl monomer whose polarity value e is not more than 1.5 in absolute value, there may be mentioned, for example, olefins; xcex1-substituted olefins; (meth)acrylic esters; and monomers having a carbon-nitrogen double bond or a carbon-nitrogen triple bond. These may be used singly or two or more of them may be used in combination or copolymerized. In the case of copolymerization, random copolymerization and block copolymerization are both possible.
Said olefin has at least one carbon-carbon double bond within the molecule. Examples are such xcex1-olefins as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene and 4-methyl-1-pentene; and dienes such as butadiene.
The xcex1-substituted olefin mentioned above may be represented by the general formula CH2xe2x95x90CY1E (wherein Y1 represents a phenyl or substituted phenyl or cyano group and E represents a hydrogen atom or an alkyl group) and, as examples, there may be mentioned styrene, xcex1-methylstyrene, xcex1-ethylstyrene, o-methylstyrene, p-methylstyrene, o-chlorostyrene, p-chlorostyrene, o-bromostyrene, p-bromostyrene, p-nitrostyrene, o-methoxystyrene, p-methoxystyrene, acrylonitrile, methacrylonitrile and the like.
Among said (meth)acrylic esters, those of the general formula CH2xe2x95x90C(R1)COOR2 [wherein R1 is a hydrogen atom or a methyl group (in the case of acrylic esters, it is a hydrogen atom and, in the case of methacrylic esters, it is a methyl group) and R2 is a univalent group selected from among aliphatic hydrocarbon groups, aromatic hydrocarbon groups, and hydrocarbon groups containing a functional group such as halogen, amine or ether] may be used efficiently. Specific examples include, but are not limited to, methyl (meth) acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth) acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, n-tridecyl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, 2-naphthyl (meth)acrylate, 2,4,6-trichlorophenyl (meth)acrylate, 2,4,6-tribromophenyl (meth)acrylate, isobornyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, diethylene glycol monomethyl ether (meth)acrylate, polyethylene glycol monomethyl ether (meth)acrylate, polypropylene glycol monomethyl ether (meth)acrylate, tetrahydrofurufuryl (meth)acrylate, 2,3-dibromopropyl (meth)acrylate, 2-chloroethyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, hexafluoroisopropyl (meth)acrylate, glycidyl (meth)acrylate, 3-trimethoxysilylpropyl (meth)acrylate, 2-diethylaminoethyl (meth)acrylate, 2-dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate, and the like.
The above-mentioned monomer containing a carbon-nitrogen double bond or a carbon-nitrogen triple bond is, for example, alkyl isocyanates and alkyl isocyanides.
As the above-mentioned compound capable of polymerizing through a ring-opening reaction, there may be mentioned cyclic ester compounds, cyclic epoxide compounds and the like and, more specifically, lactone compounds such as xcex2-propiolactone, xcex1-methyl-xcex2-propiolactone, xcex1, xcex1xe2x80x2-dimethyl-xcex2-propiolactone, xcex1-vinyl-xcex2-propiolactone, xcex3-butyrolactone, xcex4-valerolactone and xcex5-caprolactone, and propylene oxide. These may be used singly or two or more of them may be used in combination.
For obtaining a polymer from the above-mentioned vinyl monomer or the compound capable of polymerizing through a ring-opening reaction in the production method of the present invention, a copper compound is used as a catalyst either alone or incombination with an organometallic compound.
Said copper compound is represented by the general formula CuXn, LCuXn or L(Lxe2x80x2)CuXn, preferably, by the general formula LCuXna or L(Lxe2x80x2)CuXnb.
In the above formulas, L and Lxe2x80x2 each represents a ligand and X represents a halogen atom or an alkoxy, thioxy, allyloxy, amino, secondary amino, tertiary amino, cyano, nitro, alkyl or allyl group, preferably a halogen atom such as chlorine or bromine; an alkoxy group such as methoxy, ethoxy, isopropoxy or t-butoxy; or a tertiary amino group such as dimethylamino or diethylamino n is an integer of 0 to 2. na is an integer of 1 to 2. nb is an integer of 0 to 2.
The ligands L and Lxe2x80x2 are not particularly restricted but may be involved in coordinate bonding through the unpaired electron of an N, S, O or P atom occurring in the ligand structure or through a cyclopentadienyl group. More specifically, mention may be made of N-coordination, such as coordination with an amine, secondary alkylamine, tertiary alkylamine or an diimine, or amidinato coordination; and O-coordination such as coordination with an alkoxy or aryloxy group, among others.
As the N-coordination compound, there may be mentioned, for example, bipyridine, substituted bipyridine, bisoxazoline, substitued bisoxazoline; diimines represented by the general formula R3Nxe2x95x90CR4CR5xe2x95x90NR6 (wherein R3, R4, R5 and R6 each represents independently an alkyl, allyl, an aryl, a hydrogen atom, or a halogen atom; or at least one group of R3 and R4, R4 and R5, and R5 and R6 is combined and represents a cyclic group with the next carbon and/or nitrogen atom); and amidine compounds exemplified by N,Nxe2x80x2-di-substituted amidine such as N,Nxe2x80x2-dimethylamidine, N,Nxe2x80x2-diethylamidine, N,Nxe2x80x2-diisopropylamidine, N,Nxe2x80x2-di-t-butylamidine, N,Nxe2x80x2-ditrifluoromethylamidine, N,Nxe2x80x2-di-substituted phenylamidine and N,Nxe2x80x2-ditrimethylsilylamidine, N,N,xe2x80x2-di-substituted benzamidine such as N,Nxe2x80x2-dimethylbenzamidine, N,Nxe2x80x2-diethylbenzamidine, N,Nxe2x80x2-diisopropylbenzamidine, N,Nxe2x80x2-di-t-butylbenzamidine, N,Nxe2x80x2-ditrifluoromethylbenzamidine, N,Nxe2x80x2-diphenylbenzamidine, N,Nxe2x80x2-ditrimethylsilylbenzamidine and N,Nxe2x80x2-di-substituted phenylbenzamidine.
In the general formula R3Nxe2x95x90CR4CR5xe2x95x90NR6 of the diimine, the alkyl of R3, R4, R5 and R6 is exemplified by an alkyl having 1 to 6 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, pentyl, and hexyl. The aryl is exemplified by phenyl, biphenyl, and the like. The above alkyl, allyl, and aryl may be substituted by alkyl having 1 to 4 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and t-butyl; alkoxy, and the like. The halogen atom is exemplified by fluorine, chlorine, bromine, and iodine. The cyclic group is, for example, a cyclic hydrocarbon by combining R4 and R5 with the next carbon atoms and a heterocycle by combining R4 and R4, or R5 and R6 with the next carbon and nitrogen atoms. The cyclic hydrocarbon is exemplified by mono- di- or tri-cyclic hydrocarbon having 4-, 5- or 6-membered ring as each ring, and the like. The heterocycle is exemplified by mono-, di- or tri-heterocycle having 4-, 5- or 6-membered ring as each ring, and the like. A part of carbon atoms of the cyclic group may be substituted by at least one or nitrogen atom(s), sulfur atom(s), oxygen atom(s), and silicon atom(s).
The diimine of the general formula R3Nxe2x95x90CR4CR5xe2x95x90NR6 (wherein each R3 and R6 is an aryl, each R4 and R5 is a hydrogen atom, a halogen atom, an alkyl, allyl, or an aryl; or R4 and R5 are combined and represents a cyclic hydrocarbon with the next carbon atoms) is preferable. The diimine of the above general formula, wherein each R3 and R6 is an aryl and R4 and R5 are combined and represents a cyclic hydrocarbon with the next carbon atoms, is more preferable. Particularly, each R3 and R6 is preferable to be a phenyl substituted by alkyl having 1 to 4 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and t-butyl on its o- and/or m-position(s).
As the O-coordination compound with an alkoxy or aryloxy group, the O-coordination compound which coordinates with both O and N atoms of the compound at the same time, namely the O- and N-coordination compound, is preferable. As the O- and N-coordination compound, there may be mentioned, for example, 8-quinolinol, and the 8-quinolinol may be substituted.
The copper compound mentioned above may occur as the dimer or trimer or binuclear complex of a compound of the general formula CuXn, LCuXn or L(Lxe2x80x2)CuXn, preferably of the general formula LCuXna or L(Lxe2x80x2)CuXnb, which contains two or more copper atoms per molecule.
In many instances, these complexes occur in the monomer form in the solution or in the monomer at the time of reaction, although they occur as dimers, trimers or binuclear complexes in their solid state. They can be used in the present invention if said monomer state corresponds to the general formula CuXn, LCuXn or L(Lxe2x80x2)CuXn, preferably the general formula LCuXna or L(Lxe2x80x2)CuXnb.
The above copper compound can be synthesized in an easy and simple manner from an inexpensive copper halide, for example copper chloride. When the synthesis of copper(II) amidinato complexes, namely the N-coordination compounds mentioned above, is taken as an example, they can be synthesized, for example, by adding an equivalent amount of an amidine compound to anhydrous copper(II) chloride and stirring the mixture in a dry organic solvent at ordinary temperature for several hours.
In many instances, the copper compound thus synthesized is relatively stable against oxygen and moisture. In particular, bivalent copper complexes, such as N,Nxe2x80x2-dimethylbenzamidinato-copper(II) complex, can remain stable even in 100% dry oxygen, while the corresponding titanium complexes are decomposed in an atmosphere containing oxygen at a concentration of about 1%. Therefore, they can be handled very easily as compared with transition metal compounds such as titanium and zirconium compounds.
The above copper compound may be used singly or two or more of them may be used in combination.
It may be used also in a form diluted with a hydrocarbon or a halogenated hydrocarbon or the like.
The above copper compound may be used in a form supported on a granular carrier.
Useful as the granular carrier is, for example, an inorganic carrier such as SiO2, Al2O3, MgO, CaO, TiO2, ZnO and MgCl2; and a resin such as polyethylene, polypropylene and styrene-divinylbenzene copolymers.
Suitable as the organometallic compound to be used in combination with the copper compound is at least one member selected from the group consisting of aluminoxane, organoaluminum compounds represented by the general formula AlRmZ3-m (wherein R represents a hydrocarbon group containing 1 to 20 carbon atoms, Z represents a hydrogen or halogen atom or an alkoxy, allyloxy or siloxy group, and m is an integer of 0 to 3), boron-containing Lewis acids and boron-containing ionic compounds.
Among the above organometallic compounds, aluminoxanes are compounds represented by the general formula R1(Al(R1)xe2x80x94O)pAlR12 or the general formula (1) given below.
In each formula, R1 represents a hydrocarbon group containing 1 to 3 carbon atoms, and p represents an integer not less than 2. 
Among the above aluminoxane, methylaluminoxane in which R1 is a methyl group and p is not less than 5 are preferred, and those in which p is not less than 10 are more preferred. Such aluminoxanes are commercially available generally in the form of toluene solutions.
As regards the method of producing them, the direct reaction of trialkylaluminums with water and the reaction with metal salt hydrates are known.
As the organoaluminum compound represented by the above general formula AlRmZ3-m, there may be mentioned various species. More specifically, there may be mentioned trialkylaluminums such as trimethylaluminum, triethylaluminum, truisopropylaluminum, triisobutylaluminum and trioctylaluminum; alkenylaluminums such as isoprenylaluminum; dialkylaluminum monochlorides such as dimethylaluminum chloride, diethylaluminum chloride, diisopropylaluminum chloride, diisobutylaluminum chloride and dioctylaluminum chloride; alkylaluminum sesquichloride such as methylaluminum sesquichloride, ethylaluminum sesquichloride, isopropylaluminum sesquichloride, isobutylaluminum sesquichloride and octylaluminum sesquichloride; alkylalminum dichlorides such as methylaluminum dichloride, ethylaluminum dichloride, isopropylaluminum dichloride, isobutylaluminum dichloride and octylaluminum dichloride; alkoxy group-containing aluminum compounds such as methoxydiethylaluminum, diisopropoxymethylaluminum and triisopropoxyaluminum; and so forth.
As the boron-containing Lewis acid among the above organometallic compounds, there may be mentioned compounds represented by the general formula BR23 wherein R2 represents a phenyl group, which may optionally have a substituent such as a fluorine atom, a methyl group, a trifluoromethyl group or the like, or represents a fluorine atom. Specific examples are trifluoroboron, triphenylboron, tris(4-fluorophenyl)boron, tris(3,5-difluorophenyl)boron, tris(4-fluoromethylphenyl)boron, tris(pentafluorophenyl)boron, tris(p-tolyl)boron, tris(o-tolyl)boron, and tris(3,5-dimethylphenyl)boron. Among these, tris(pentafluorophenyl)boron is preferred.
As the boron-containing ionic compound among the above organometallic compounds, there may be mentioned, for example, trialkyl-substituted ammonium salts, N,N-dialkylanilinium salts, dialkylammonium salts and triarylphosphonium salts.
As specific examples, there may be mentioned trialkyl-substituted ammonium salts such as triethylammonium tetra(phenyl)boron, tripropylammonium tetra(phenyl)boron, tri(n-butyl)ammonium tetra(phenyl)boron, trimethylammonium tetra(p-tolyl)boron, trimethylammonium tetra(o-tolyl)boron, tributylammonium tetra(pentafluorophenyl)boron, tripropylammonium tetra(o,p-dimethylphenyl)boron, tributylammonium tetra(m,m-dimethylphenyl)boron, tributylammonium tetra(p-trifluoromethylphenyl)boron and tri(n-butyl)ammonium tetra(o-tolyl)boron; N,N-dialkylanilinium salts such as N,N-dimethylanilinium tetra(phenyl)boron, N,N-diethylanilinium tetra(phenyl)boron and N,N,2,4,6-pentamethylanilinium tetra(phenyl)boron; dialkylammonium salts such as di(1-propyl)ammonium tetrapentafluorophenylboron and dicyclohexylammonium tetra(phenyl)boron; triarylphosphonium salts such as triphenylphosphonium tetra(phenyl)boron and tri(dimethylphenyl)phosphonium tetra(phenyl)boron; and the like. Further examples are triphenylcarbenium tetrakis(pentafluorophenyl)boronate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, ferrocenium tetra(pentafluorophenyl)borate and the like.
Further, such anion salts as listed below may also be mentioned as examples of the boron-containing ionic compounds [in the ionic compounds listed below, the counter ion is typically given as, but is not limited to, tri(n-butyl)ammonium]. Such salts of anions include, for example, bis[tri(n-butyl)ammonium] nonaborate, bis[tri(n-butyl)ammonium] decaborate, bis[tri(n-butyl)ammonium] undecaborate, bis[tri(n-butyl)ammonium] dodecaborate, bis[tri(n-butyl)ammonium] decachlorodecaborate, bis[tri(n-butyl)ammonium] dodecachlorododecaborate, tri(n-butyl)-ammonium 1-carbadecaborate, tri(n-butyl)ammonium 1-carbaundecaborate, tri(n-butyl)ammonium 1-carbadodecaborate, tri(n-butyl)ammonium 1-trimethylsilyl-1-carbadecaborate, tri(n-butyl)ammonium bromo-1-carbadodecaborate and, further, borane and carborane complexes; carborane anion salts; carboranes and carborane salts, for instance.
Furthermore, such metal carborane salts and metal borane anions as listed below may also be mentioned as examples of said boron-containing ionic compound [in the ionic compounds listed below, the counter ion is typically given as, but is not limited to, tri(n-butyl)ammonium].
Said metal carborane salt and metal borane anion include, among others, tri(n-butyl)ammonium bis(nonahydrido-1,3-dicarbanonaborate) cobaltate(III), tri(n-butyl)ammonium bis(undecahydrido-7,8-dicarbaundecaborate) ferrate(III), tri(n-butyl)ammonium bis(undecahydrido-7,8-dicarbaundecaborate) cobaltate(III), tri(n-butyl)ammonium bis(undecahydrido-7,8-dicarbaundecaborate) nickelate(III), tri(n-butyl)ammonium bis(undecahydrido-7,8-dicarbaundecaborate) cuprate(III), and the like.
In the catalyst system in the present invention, there may be incorporated, when necessary, an electron-donating compound such as ethyl benzoate. The addition of such a compound may sometimes lead to a marked increase in polymerizing activity.
The details of the polymerization mechanisms in the production method of the present invention are not clear. It is presumable, however, that the copper compound serves as a catalyst and/or polymerization initiator and that the interaction between the copper compound alone or the copper compound and organometallic compound, on one hand, and the vinyl monomer or the compound capable of polymerizing through a ring-opening reaction (hereinafter, collectively referred to as xe2x80x9cmonomerxe2x80x9d) on the other accelerates the coordination and insertion reactions of the monomer.
The above copper compound alone or the copper compound and organometallic compound may be added to the reaction system before, simultaneously with, or after monomer introduction, but preferably before monomer introduction. The polymerization technique and conditions, among others, are not particularly restricted. The polymerization may be carried out continuously or noncontinuously.
The polymerization for obtaining the above polymers is preferably carried out in an inert gas atmosphere. Useful as said inert gas are nitrogen, helium and argon, among others.
The solvent to be used in the polymerization includes, among others, halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride and dichloroethane; hydrocarbons such as benzene, toluene and xylene; tetrahydrofuran, dioxane, dimethylformamide and the like. It is also possible to carry out the polymerization without using any solvent.
The polymerization temperature is preferably within the range from the melting point of the solvent used to the boiling point thereof. If under pressurization, the polymerization can be carried out within a wider temperature range extending to a higher temperature than the boiling point at ordinary pressure.
For example, even at room temperature, polymers with a narrow molecular weight distribution can be obtained.
To be concrete, it is generally preferred that the polymerization temperature be xe2x88x9220xc2x0 C. to 200xc2x0 C., more preferably 0xc2x0 C. to 120xc2x0 C. As for the polymerization pressure, it is generally preferred that it be within the range of atmospheric pressure to 100 kg/cm2, more preferably from atmospheric pressure to 50 kg/cm2.
In cases where the copper compound is used alone as the catalyst, it is generally preferred that it be used in an amount of about 0.00005 to 0.5 millimole, more preferably about 0.0001 to 0.05 millimole, as calculated on the copper atom basis, per liter of polymerization volume.
In cases where the copper compound and organometallic compound are combinedly used as the catalyst, the copper compound is preferably used in the same amount as in the case of single use of the copper compound and, as regards the organometallic compound, it is generally preferred that when it is an aluminum compound, it be used in an amount of about 1 to 10,000 moles, more preferably 10 to 5,000 moles, as calculated on the aluminum atom basis, per mole of the copper atom in the copper compound. In the case of a boron-containing Lewis acid or ionic compound, it is generally preferred that it be used in an amount of 1 to 500 moles, more preferably 1 to 100 moles, as calculated on the boron atom basis, per mole of the copper atom in said copper compound.
The molecular weight of the product polymer can be controlled by modifying the polymerization temperature and other conditions or by other known means, for example the use of hydrogen.
By using such a polymerization catalyst as mentioned above, it is possible to obtain polymers excellent in composition distribution in the same manner as in the case of using other transition metal complex catalysts. Actually, it can be confirmed by polymer analysis by gel permeation chromatography (GPC) that the polymers obtained by the production method of the present invention have a molecular weight distribution (Mw/Mn) as narrow as 1.1 to 3.5, indicating the progress of polymerization in a precisely controlled manner.
The following examples illustrate the present invention in further detail. However, these examples are by no means limitative of the scope of the present invention.